Open cell porous material and method for producing same

Abstract

An open cell porous material and a method for producing it is provided. The porous material of the present invention is generally composed of particles of at least one inorganic material bonded together by a brazing agent, generally provided as inorganic brazing alloy particles. The porous material is produced by heating a mixture comprising inorganic brazing alloy particles having a first melting temperature, inorganic particles having a second melting temperature higher than the first melting temperature, a binding agent having a decomposition temperature lower than the first melting temperature and preferably a foaming agent. In practice, the mixture is heated to induce foaming thereof via the foaming agent. The solid foamed structure is then heated at the decomposition temperature to substantially eliminate the binder. The resulting foamed structure is then heated again at about the first melting temperature to melt the inorganic brazing alloy particles in order to bond together the remaining three-dimensional network of inorganic particles into a rigid structure having interconnected porosity.

1 .- 134 . (canceled) 
   
   
       135 . A method for making an open cell porous body comprising:
 a. providing a mixture including:
 i. a first predetermined amount of inorganic brazing particles having a first melting temperature; 
 ii. a second predetermined amount of inorganic particles having a second melting temperature, the second melting temperature being higher than the first melting temperature, the inorganic particles being adapted to be brazed by the brazing particles; and 
 iii. a third predetermined amount of a binding agent having a decomposition temperature, the decomposition temperature being lower than the first melting temperature; 
   b. heating the mixture to at least the decomposition temperature to decompose the binding agent and obtain an unbrazed open cell porous body; and   c. heating the unbrazed open cell porous body in a reducing atmosphere to at least the first melting temperature to melt the inorganic brazing particles and cause the melted inorganic brazing particles to create metallic bonds between the inorganic particles.   
   
   
       136 . A method for making an open cell porous body as recited in  claim 135 , wherein the inorganic brazing particles consist essentially of metal or metal alloy particles. 
   
   
       137 . A method for making an open cell porous body as recited in  claim 135 , wherein the inorganic brazing particles consist essentially of silver-based brazing alloy particles. 
   
   
       138 . A method for making an open cell porous body as recited in  claim 137 , wherein the silver-based brazing alloy particles include copper. 
   
   
       139 . A method for making an open cell porous body as recited in  claim 138 , wherein the silver content of the silver-based brazing alloy particles is between about 56% by weight to about 100% by weight and a remainder is copper. 
   
   
       140 . A method for making an open cell porous body as recited in  claim 135 , wherein the first predetermined amount is between about 1 wt % to about 60 wt % inclusive of a total weight of the mixture. 
   
   
       141 . A method for making an open cell porous body as recited in  claim 140 , wherein the first predetermined amount is between about 5 wt % to about 45 wt % inclusive of the total weight of the mixture. 
   
   
       142 . A method for making an open cell porous body as recited in  claim 135 , wherein heating the unbrazed open cell porous body in a reducing atmosphere to at least the first melting temperature to melt the inorganic brazing particles and cause the melted inorganic brazing particles to create metallic bonds between the inorganic particles is carried out in an absence of flux. 
   
   
       143 . A method for making an open cell porous body as recited in  claim 135 , wherein the mixture further includes a fourth predetermined amount of a foaming agent; the method further comprising heating the mixture to induce foaming thereof before heating the mixture at the decomposition temperature to decompose the binding agent and obtain an unbrazed open cell porous body. 
   
   
       144 . A method for making an open cell porous body as recited in  claim 143 , wherein the inorganic brazing particles consist essentially of metal or metal alloy particles. 
   
   
       145 . A method for making an open cell porous body as recited in  claim 143 , wherein the inorganic brazing particles consist essentially of silver-based brazing alloy particles. 
   
   
       146 . A method for making an open cell porous body as recited in  claim 145 , wherein the silver-based brazing alloy particles include copper. 
   
   
       147 . A method for making an open cell porous body as recited in  claim 146 , wherein the silver content of the silver-based brazing alloy particles is between about 56% by weight to about 100% by weight and a remainder is copper. 
   
   
       148 . A method for making an open cell porous body as recited in  claim 143 , wherein the first predetermined amount is between about 1 wt % to about 60 wt % inclusive of a total weight of the mixture. 
   
   
       149 . A method for making an open cell porous body as recited in  claim 148 , wherein the first predetermined amount is between about 5 wt % to about 45 wt % inclusive of the total weight of the mixture. 
   
   
       150 . A method for making an open cell porous body as recited in  claim 143 , wherein heating the unbrazed open cell porous body in a reducing atmosphere to at least the first melting temperature to melt the inorganic brazing particles and cause the melted inorganic brazing particles to create metallic bonds between the inorganic particles is carried out in an absence of flux. 
   
   
       151 . An open cell porous body made according to the method recited in  claim 143 . 
   
   
       152 . An open cell porous body made according to the method recited in  claim 135 . 
   
   
       153 . A mixture for making open cell porous bodies, the mixture comprising:
 a. a first predetermined amount of inorganic brazing particles having a first melting temperature;   b. a second predetermined amount of inorganic particles having a second melting temperature, the second melting temperature being higher than the first melting temperature, the inorganic particles being adapted to be brazed by the brazing particles; and   c. a third predetermined amount of a binding agent having a decomposition temperature, the decomposition temperature being lower than the first melting temperature;   
   
   
       154 . A mixture as recited in  claim 153 , further comprising a fourth predetermined amount of a foaming agent.